Can anyone please advise the cylinder head stud thread size on a 1960 650cc AJS model 31, please.
Thread Size
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Thread Size
They have a different thread at either end, BSF into the crankcase BSC (cycle) for the nuts. Both 5/16" dia or perhaps 3/8" as sometime around then there was a factory change and some owners also opened out earlier ones as well, the idea was to get more torque on the head studs to help prevent gaskets blowing.